i had about 500 dna before the badges appeared. then the badges came and i kept the dna i ad but i had to get another thousand. the 500 i already had didn't count!!!
for me this strategy seems to work: Stay at the villiage you spawn at. buy sam missiles. then buy castle. Go towards the enemy while firing sam missiles. when you get close to enemy/enemy villiage use the castle. Then once you have captured two villiages (so there is only one left) buy the aircraft carrier and use it to anihalate the last villiage.
wow the last fight is really easy compared to the fight before it. it took me 8 tries to complete the second last fight and i won the last fight 1st time.